North Korea continues to sustain an estimated 20 undeclared missile operating bases, and a U.S. think tank says it has identified at least 13 of them. Sakkanmol, a site identified as close to the border with South Korea, appears to be “active and being reasonably maintained,” the report said.

(Pictured: A television news station broadcasts a picture of the dismantling of North Korea’s Punggye-ri nuclear test site. North Korea said it had fully demolished its only known nuclear test site in May 2018.)

The Center for Strategic and International Studies (CSIS) report said improvements to infrastructure and other maintenance have occurred at these facilities in the wake of ongoing negotiations to denuclearize North Korea.

“While some of the information used in the preparation of this study may eventually prove to be incomplete or incorrect, it is hoped that it provides a new and unique open-source look into the subject that others may build on,” the November 2018 report stated.

Within days of the CSIS report, news came that North Korea leader Kim Jong Un oversaw testing of a “newly developed ultramodern tactical weapon,” leaving analysts to wonder what else the regime could be hiding and what message Kim is trying to send.

“They’re trying to signal that they are willing to walk away from talks and restart weapons testing,” opined Adam Mount, a member of the Federation of American Scientists, according to Voice of America News. “It is the most explicit in a series of escalating statements designed to send this message.”

A U.S. State Department spokesman, however, said the test would not derail efforts to persuade North Korea to give up its nuclear weapons program.

“We remain confident that the promises made by President [Donald] Trump and Chairman Kim [Jong Un] will be fulfilled,” the U.S. State Department spokesman said, according to Voice of America.

Multiple news reports said Kim visited North Korea’s Academy of Defense Science to supervise testing of a “state-of-the-art weapon” developed under his leadership to safeguard North Korean territory and “significantly” improve the combat power of the North Korean army.

Little else is know about the weapon, but experts say it did not appear to be the type of long-range missiles frequently fired by the North. What remains to be seen is whether the North desired the test to be a less provocative message that it intends to continue developing weapons for self-defense.

“It may be that the North is releasing a little bit of information with the purpose of enhancing its leverage in negotiations that are likely to take place in the future,” Han Yong-sup, a professor at the Korea National Defense University, told Stars and Stripsnewspaper. “What they are saying is, ‘We’ll keep developing weapons like this unless the outside world or the U.S. takes corresponding measures.’”

As for the CSIS report, its researchers and authors Joseph Bermudez, Victor Cha and Lisa Collins, used satellite imagery to identify remote sites scattered in mountainous areas across North Korea. These sites could be used for all classes of ballistic missile from short-range up to and including intercontinental ballistic missiles.

“Missile operating bases are not launch facilities,” Bermudez wrote. “While missiles could be launched from within them in an emergency, Korean People’s Army (KPA) operational procedures call for missile launchers to disperse from the bases to pre-surveyed or semi-prepared launch sites for operations.”

Missile operating bases are permanent facilities that contain a unit’s headquarters, barracks, housing, support maintenance and storage, the report said. North Korea’s military policy dictates that it remains in a state of war, and its missile operating bases display distinct characteristics, the report outlined. Among them:

They are generally rudimentary, and except for headquarters and cultural structures, possess few large buildings or paved roads.

With only a few exceptions, they are in mountainous terrain, often spread out within narrow dead-end valleys. This often results in their lacking significant physical security measures and having only a basic entrance security checkpoint.

Excluding their associated agricultural support infrastructure, they are physically small.

They almost always consist of a network of underground facilities to house the unit’s transporter-erector-launchers (TELs) or mobile-erector-launchers (MELs), a ready inventory of missiles and warheads and other technical/launch support vehicles and equipment.

They are not launch facilities. While missiles could be launched from within these bases in an emergency, KPA ballistic missile tactics and doctrine call for TELs and MELs to disperse from missile operating bases to pre-surveyed and semi-prepared launch sites for operations.

These bases simply do not have the appearance of missile operating bases as seen in the United States, Russia, China or Europe.

North Korea has not acknowledged any of these bases, according to Reuters. Doing so, analysts say, is an important part of any denuclearization deal.